After the shots: a reading guide

Medically-informed · Sources: CDC · Updated June 2026 · 3 min read

The normal after-picture

Commonly seen in the 24–48 hours after two-month vaccines: extra sleepiness, mild fussiness, reduced appetite, tenderness or a small firm bump at injection sites. All of it says the immune system took the assignment.

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Comfort protocol

More holding, more feeds, a quiet day. The site bump can last a couple of weeks and needs nothing. Don't pre-dose fever medicine 'just in case' — give it only if your pediatrician advises for actual discomfort.

Is this normal for your baby?

FirstWeeks answers with your baby’s age and today’s log in mind — with pediatric sources attached.

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The fever line

Under three months, 100.4°F (38°C) or higher is always a same-day call — vaccine day or not. Measure rectally for accuracy at this age; forehead strips underperform exactly when it matters.

Call now signals

Inconsolable crying beyond three hours, limpness or unresponsiveness, hives or facial swelling, or anything your gut flags as wrong — call. Serious reactions are rare; asking is always free.

Log the reaction

Note in Medicine what happened and when — the pattern makes the four-month round predictable instead of scary.